In have a branch site presently connected via SDSL utilising a Cisco 888 router. This router has the fixed physical interfaces with a ATM0 interface and a bank of 4 fastethernet acting as a four port switch running VLAN1.
At present the ATM0 is the "Outside" running the SDSL and the FE0-3 is the "Inside" running a interface VLAN1. BGP is running on the SDSL interface.
The site is due to have it's external SDSL link replace by a 10Mb circuit which will be presented as a RJ45.
My question is to save the cost of a new router can anyone see any issues by not using a dedicated physical interface for the outside link but using the four port switch on the router for both the "Inside" and "Outside" links, with two VLAN interfaces configured ie interface VLAN2 as the "Outside" and interface VLAN1 as the "Inside". BGP would be required to run on the outside interface as before.
So the setup would be something like.....
Interface Fe0 in VLAN1 connected to the inside.
Interface Fe1 in VLAN2 connected to the outside also running BGP.